Workshop on the determination of centrality in pA collisions at the LHC

Europe/Zurich
4/3-006 - TH Conference Room (CERN)

4/3-006 - TH Conference Room

CERN

100
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Andreas Morsch (CERN)
Description
The analysis of pPb collisions allows for the study of cold nuclear effects in order to establish a baseline for the interpretation of heavy ion results. Nuclear modification factors in minimum bias pPb collisions with respect to the pp reference have been measured at LHC for a large variety of probes ranging from inclusive hadrons to heavy flavors and jets. To measure the centrality dependence of these observables, the binary scaling factors (Ncoll) between pp and p-Pb have to be determined for each centrality class. Since the pA@LHC workshop organized in June 2012 in front of the first pPb data taking at the LHC, it has become clear that due to the looser correlation between centrality estimators and Ncoll, centrality determination in pPb is a delicate task. Kinematic biases on the centrality dependent observables can not be excluded and need special attention. Two recent conferences, IS2013 and Hard Probes 2013, had discussion sessions on centrality determination in p(d)A collisions as part of their program demonstrating the importance of this topic. These discussions have not yet come to a conclusion. The procedures developped by the LHC experiments are quite different, while first preliminary results on centrality dependent nuclear modification factors have already been presented. The aim of this Workshop is to start a more formal discussion, to be carried on by the studies of this inter-experiments Working Group, with the goal of formulating a common approach to the definition, determination and use of centrality in pA events.

Working Group conveners:
ALICE: Andreas Morsch (chair)
ATLAS: Brian Cole and Dennis Perepelitsa
CMS: Shengquan Tuo
LHCb: Michael Schmelling and Burkhard Schmidt
Theory: Carlos Salgado
Participants
  • Alberica Toia
  • Alexander Borissov
  • Alexander Duplinskiy
  • Alexander Philipp Kalweit
  • Alice Ohlson
  • Alis Rodriguez Manso
  • Andrea Dubla
  • Andreas Morsch
  • Anna Julia Zsigmond
  • Antonio Uras
  • attilio tarantola
  • Brian Cole
  • Carlos Salgado
  • Chiara Oppedisano
  • Christopher Ryan Edwards-Bruner
  • Constantinos Loizides
  • Cvetan Valeriev Cheshkov
  • Daniil Ponomarenko
  • Dennis Perepelitsa
  • Doga Can Gulhan
  • Emilia Leogrande
  • Ferenc Siklér
  • Friederike Bock
  • Gian Michele Innocenti
  • Grigori Feofilov
  • Hannes Wessels
  • Igor Altsybeev
  • Jan Fiete Grosse-Oetringhaus
  • Jan Rak
  • Jason Kamin
  • Jonas Anielski
  • Ken Oyama
  • Ladislav Sandor
  • Leonardo Milano
  • Mark Strikman
  • Marta Verweij
  • Mateusz Ploskon
  • Matthew Nguyen
  • Michael Murray
  • Michael Schmelling
  • Michael Weber
  • Michele Floris
  • Mohammed Mahmoud Mohammed
  • Mohd. Danish Azmi
  • Nora De Marco
  • Pedro Ladron De Guevara
  • Per-Ivar Lønne
  • Peter Hristov
  • Pietro Cortese
  • Raghav Kunnawalkam Elayavalli
  • Riccardo Russo
  • Rudiger Haake
  • Ryan White
  • Shengquan Tuo
  • Sunil Manohar Dogra
  • Vladimir Kovalenko
  • William Brooks
  • Yen-Jie Lee
  • Yetkin Yilmaz
Videoconference Rooms
Workshop_on_the_determination_of_centrality_in_pA_collisions_
Name
Workshop_on_the_determination_of_centrality_in_pA_collisions_
Description
The analysis of p-Pb collisions allows for the study of cold nuclear effects in order to establish a baseline for the interpretation of heavy ion results. Nuclear modification factors in minimum bias p-Pb collisions with respect to the pp reference have been measured at LHC for a large variety of probes ranging from inclusive hadrons to heavy flavors and jets. To measure the centrality dependence of these observables, the binary scaling factors (N_coll) between pp and p-Pb have to be determined for each centrality class. Since the pA@LHC workshop organized in June 2012 in front of the first p-Pb data taking at the LHC, it has become clear that due to the looser correlation between centrality estimators and N_coll, centrality determination in p-Pb is a delicate task. Kinematic biases on the centrality dependent observables can not be excluded and need special attention. Two recent conferences, IS2013 and Hard Probes 2013, had discussion sessions on centrality determination in p(d)-A collisions as part of their program demonstrating the importance of this topic. These discussions have not yet come to a conclusion. The procedures developped by the LHC experiments are quite different, while first preliminary results on centrality dependent nuclear modification factors have already been presented. The aim of this Workshop is to start a more formal discussion, to be carried on by the studies of this inter-experiments Working Group, with the goal of formulating a common approach to the definition, determination and use of centrality in pA events. Working Group conveners: ALICE: Andreas Morsch (chair) ATLAS: Brian Cole and Dennis Perepelitsa CMS: Shengquan Tuo LHCb: Michael Schmelling and Burkhard Schmidt Theory: Carlos Salgado
Extension
109292366
Owner
Andreas Morsch
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Useful links
Phone numbers
    • 08:30 09:00
      pPb Centrality in ATLAS 30m
      Speaker: Brian Cole (Columbia University (US))
      Slides
    • 09:10 09:40
      pPb Centrality in CMS 30m
      Speaker: Shengquan Tuo (Vanderbilt University (US))
      Slides
    • 09:50 10:20
      pPb Centrality in ALICE 30m
      Speaker: Chiara Oppedisano (Universita e INFN (IT))
      Slides
    • 10:30 11:00
      Coffee Break 30m
    • 11:00 11:30
      pPb Centrality in LHCb 30m
      Speaker: Michael Schmelling (Max-Planck-Gesellschaft (DE))
      Slides
    • 11:40 12:10
      Modelling of interplay between hard and soft processes in pp 30m
      Speaker: Peter Skands (CERN)
      Slides
    • 12:20 12:50
      Glauber-Gribov Model and centrality determination 30m
      Speaker: Mark Strikman (Pennsylvania State University (US))
      Slides
    • 13:00 14:30
      Lunch 1h 30m
    • 14:30 16:30
      Discussion Session 2h
      Slides
    • 16:30 17:00
      Coffee Break 30m
    • 17:00 18:30
      Centrality dependent measurements
      • 17:00
        Centrality dependent measurements ATLAS 20m
        Speaker: Dennis Vadimovich Perepelitsa (Brookhaven National Laboratory (US))
        Slides
      • 17:30
        Centrality dependent measurements CMS 20m
        Speaker: Yetkin Yilmaz (Laboratoire Leprince-Ringuet, France)
        Slides